Refrigerator evaporator



` Jan. 6, 1943.v

C. E. HICKMAN REFRIGERATOR EVAPORATOR Filed May 18, 1946 :s sheets-sheet1 .lim

Array/vir Jam 6 1948- c. E. HICKMAN REFRIGERATOR EvAPoRAToR Filed May18, 1946 3 Sheets-Sheet 2 INVENToR. FM4/Pz s Mc/mmm Mazzi;

Jan l6 1948' c. E, HICKMAN REFRIGERATOR EVAPORATOR lFiled May 18, 1946 3Sheets-Sheet 3 INVENTOR.

m M m M fr.. m W C ATTORNEY Patented Jan. 6, 1948 UNITED STATES PATENTOFFICE 18 Claims.

This invention relates to an improved evaporator which is particularlyadapted for use in household refrigerators, although certain of itsfeatures may be useful in evaporators of other types.

The evaporator of the present invention is mainly formed from extrudedmaterial as suggested in the prior patents to Ackerman, 1,969,813,issued August '7, 1934, and Booth, 2,212,912, issued August 27, 1940.The main body of the evaporator is formed from a sheet of materialoriginally extruded With a plurality of spaced conduits formed therein,which sheet may be used in any preferred shape. The present inventionrelates particularly to header constructions that are of particularutility with this style of evaporator.

A feature of the invention resides in the use for the distributingheader of a special extruded shape particularly adapted to permitsimplified attachment by oven brazing.

Another feature is to be found in the construction of the accumulatingheader, which also is Well adapted to assembly by oven brazing.

While preferred forms of the invention are disclosed herein by way ofillustration, it should be understood that various changes may be madein the structure without departing from the spirit and scope of theclaims.

In the drawings:

Fig. 1 is a perspective view of an evaporator embodying the invention.

Fig- 2 is a perspective of the extruded shape from which the body of theevaporator is formed.

Fig. 3 is an exploded fragmentary view illustrating the construction andattachment of the distributing header.

Fig. 4 is a fragmentaryyiew, partly in crosssection, illustratingfurther the construction of the distributing header and associatedpassages.

Fig. 5 is a cross-section taken 0n line 5-5 of Fig. 4.

Fig. 6 is a fragmentary perspective partly broken away showing theconstruction of the accumulating header.

Fig. '7 is a view similar to Fig. 5 illustrating possible modifications.

Fig. 8 is a view similar to Fig. 5 but illustrating additionalvariations in the structure.

Fig. 9 is a fragmentary perspective showing certain modifications asapplied to an accumulating header.

Fig. 10 is a cross-section taken on line Ill-I0 of Fig. 9.

Fig. 11 is an end elevation of a U-shaped `evaporator with adistributing header located at the bottom of the U, and an accumulatingheader located at the upper end of each side of the U.

Fig. 12 is an exploded fragmentary perspective illustrating theconstruction of the distributing header of Fig. 9.

The present application which is led to replace my prior-led applicationSer. No. 576,828 now abandoned, is a duplicate of the prior-liledapplication except that Figs. 9 and 10 have been added. The presentapplication is therefore a continuation in-part of said abandoned Ser.No. 576,828.

Referring to the drawings more particularly, Figs. l to 6 inclusiveillustrate a preferred form of the invention, Which is designed for usein a household refrigerator. For purposes of illustration the dimensionsgiven herein are presently preferred for use in an evaporator for ahousehold refrigerator of average size, namely 7 to 8 cu. ft. capacity.The evaporator, which is shown in a general view in Fig. 1, comprises amain body portion I0, a distributing header II, and an accumulatingheader I 2.

A primary step in the manufacture of the evaporator is to extrude astrip or plate of material having the shape illustrated in Fig. 2. Thisshape as illustratedrhas a fiat face I3 and longitudinal ribs I4projecting from the opposite face of the sheet. These ribs I4 are joinedtogether by the relatively thin Webs I5 and are contoured so as to givethis face of the sheet a smooth and pleasing appearance. Thelongitudinal ribs I4 are pierced by conduits I6 which conduct therefrigerating uid in a manner which will be subsequently explained. Oneedge of the extruded shape carries a finishing bead Il while theopposite edge carries bead I8 which is somewhat heavier than the beadII. The shape illustrated in Fig. 2 is extruded in a long strip from anysuitablematerial, such as commercially pure aluminum. It may be ofsuitable widths for particular designs and it may carry as many of theconduits I6 as considered desirable.

The conduits IB are given a fiat rectangular shape since this shape hasthe advantages ofre- K ducing the height of the longitudinal ribs I4 andtruded shape 24 inches long would be cut off for the evaporatorillustrated in Fig. 1.

A particular feature of the invention resides in the construction of thedistributing header II and its attachment to the main body II). The

header II is formed from an extruded section having a cross-sectionalshape which, as shown in Figs. 3 and 5, includes a tubular body I9 whichhas a flat face 20 adapted to engage a flat end surface of the main bodyIIJ, and which has an offset flange 2i which carries a flat face adaptedto engage the flat surface I3 of the main body IIB. Along the line ofjunction between the offset flange 2i and the body I9, a groove 22 isformed which is adapted to receive a piecevof braZing wire. The outershape of the extrusion for the distributing header is contoured toaccommodate the groove 22, preferably by a projectingl rib 23. Thisshape for the distributing header II is also preferably extruded fromcommercially pure aluminurn.

Prior to the assembly of distributing header II with the main body I3 aplurality of orifices 24 are drilled through the flat face 20 so as tocommunicate with the cylindrical passage 25 of the body I9. The orifices24 are located so that when the distributing header II is assembled withthe mainbody ID, as shown in Fig, 5, each of the oriiices 24 registerswith one of the longitudinal conduits IS as clearly shown in Fig. 4. Theorifices 2 4 are preferably from 1/8 in. to in. in diameter, the lattersize being the smallest that can be used in the present constructionWithout danger of the orifice becoming filled with brazing material bycapillary action during the subsequent brazing operation. Thecylindrical passage 25 is approximately Tse in. in diameter. Thisdiameter should be slightly larger than the combined areas of theorifices 24 in order to maintain proper liquid supply to these orifices,but it should be kept as small as possible in order to minimizeevaporation of the liquid refrigerant before it reaches the oriiices, Bythus insuring that substantially no gas passes through the orices 24 auniform distribution of the refrigerant to the conduits IE is assured.

The process o-f attaching the distributing header -I I to the main bodyI starts with filling groove 2,2 with a suitable brazing material whichhas a slightly lower melting point than the melting point of thecommercially pure aluminum used for parts Il) and I I. This brazingmaterial, which may be an alloy of aluminum containing a smallpercentage of silicon, may be introduced into groove 22 in the shape ofwire 26. The distributing header II Vis then assembled on main body II)to the position illustrated in Figs. 4 and 5, in which the at face 25 ofdistributing header II engages one of the at end surfaces of main body Iand the inner fiat face of the offset flange 2! engages the fiat surfaceI3 of main body III. The parts may be temporarily held in this assembledrelation in any preferred manner, as by tacking them together withseveral 'spot wel-ds. A closure plug 21 is inserted 'in one end of thecylindrical passage 25, while the liquid inlet line 28 is inserted inthe other end, plug l21 and line 28 both being suitably supplied withbrazing material. Subsequently, after other parts have been put intoplace for brazing, the complete assembly is ovenbrazed at a temperaturewhich causes the brazing material to melt and run by capillary actionbetween the contacting surfaces, producing a strong and leak-proof jointlat all area of contact.

Another feature of the invention resides in the construction of theaccumulating header I2 and its attachment to the main body II] asillustrated in Fig. 6. The accumulating header is formed from a roundtube approximately 1%. in. in diameter formed of commercially purealuminum. Prior to the assembly of accumulator I2 with the evaporator,the appropriate end of main body I0 is prepared as illustrated in Fig.6. This preparation consists of cutting back the Webs I5 for a shortdistance between the ribs I4 so as to leave the ends of these ribsprojecting as short tubular extensions from the main body I0. Theseextensions will have the same shape they had when they were a part ofthe main body I0, that is, they will have a substantially D-shape with aflat face corresponding t0 the flat surface I3 of the main body, andwith a rounded upper face correspond- -ing to the contoured surface ofthe main body.

The tube which is to form the accumulating header I2 is prepared forassembly by forming in its wall a series of D-shaped holes correspondingin shape with the projecting ends of ribs I4 and spaced so as to exactlyregister with these projecting ends. The accumulating header is thenassembled with the main body Ill by inserting the projecting ends ofribs Id in the holes that have been formed in header I2 and brazingcompound is suitably paced so that during the subsequent brazingvoperation all the areas of contact between the accumulating header I2and the main `body I3 are covered by brazing compound, forming afluid-tight seal. One end of the header I2 is closed by brazlng withinit a closure cap 29 whilei-n the other end is brazed a cap 30 aperturedto receive the gas return line 3|.

In order to provide a liquid trap within the accumulating header apartition in the form of a cup-shaped disk 32 is brazed Within theheader near its outlet end. This disk is formed with a small aperture 33which is positioned so as to be at the to-p of the header when theevaporator is in its iinal installed position. The construction of theheader is such that when the refrigerating apparatus is on the offcycle, the conduits I6 may be comp-etely hooded and there may be a smallsurplus of liquid refrigerant in the accumulator lf2, but at the sametime the trap provided by disk 32 insures that none of the liquid willbe drawn from the header into the return line 3I when the compressorbegins to operate. This arrangement increases eiciency and promotesuniformity'of vfrosting of the evaporator.

:It should be 'understood of course that while the 'construction justdescribed for the accumulating header lI2 is aipresently preferredconstruction, this header may be formed and attached in any suitablemanner, vas for example, in the manner described in connection with thedistributing header II.

In order to `form the type of evaporator illustrated in Fig. 1, thesheet of extruded material forming the :mai-n `body I0 is bent up intoU-shape with lthe `ribs I4 on the outside, as clearly shown in Fig. 1.The liquid line 28, which conducts liquid refrigerant to thedistributing header I I, may pass along the under side of a shelf 34 asshown. After vall of the parts have been assembled to the positionillustrated in Fig. 1 and the brazing compound described above has beenIapplied Wherever necessary, the assembly can be oVen-brazed in a mannerwell known in the art. This brazing process joins all of the aluminumparts together so that the completed evaporator is an integral,substantially homogeneous mass of aluminum 5 with no joints or otherdiscontinuities to interfere with eilicient heat flow throughout themass.

In the completed evaporator, liquid refrigerant flows from the liquidline 28 to the distributing header I I, whence it is fed through theorifices 24 into the conduits I6 of the main body I0 of the evaporator.The gas produced by evaporation of the liquid refrigerant collects inthe accumulating header I2 and is drawn oil by the compressor throughthe return line 3|. The compressor and other parts of the refrigeratingmechanism, being conventional, are not illustrated, and of course anyother suitable means for circulating liquid and gaseous refrigerant maybe used.

The inlet line 28 and the return line 3| project from the rear of theevaporator, which carries the lighter finishing bead Il. The heavierbead I8 is at the'front of the evaporator where it may be used to attacha door if desired.

While the improvements of the present invention have been illustrated inconnection with a U-shaped evaporator it will be clear to those skilledin the art that the evaporator can be given other shapes suitable forparticular installations.

Various modifications of the structure above described are within thescope of the invention. For example, Fig. 7 illustrates a variation inthe construction of the distributing header. In this case the groove 22afor the brazing material is formed in the face of distributing headerIIa which contacts the end face of the main body I and the oflset flangeZia extends straight down parallel to the ilat face I3 of body I0thereby avoiding the presence of the projecting rib 23. This alternateconstruction shown in Fig. 7 thus eliminates the presence of theprojecting rib 23 although it requires some additional space in the mainbody of the distributing header to accommodate the brazing material.

Fig. 8 shows how a construction similar to that illustrated in Figs. and7 can be utilized in other types of evaporators. In this constructionthe strip 35 has two conduits 36 and 31 formed therein, the conduit 36being in communication with the conduits of a main body 38 similar inconstruction to the main body Il] illustrated in Figs. 1 to 5 inclusive,while the opposite ends of the conduits of body 38 are in communicationwith the conduit 37 of the strip 35. Strip 35 carries a flange 39 forattachment to one end of body 38 and a ilange 4i] for attachment to theother end of body 38. By blocking off the conduits 36 and 31 at suitablepoints this construcion can be utilized for a continuous-tube type ofevaporator.

Several other permissible variations are illustrated in Figs. 9 and 10,which show an accumulating header I2b. In this form the header isextruded as a shape having the cross-section shown in Fig. in which thecylindrical body carries an oiset flange 2| b, which serves the samepurpose as flange 2| of Fig. 5. However, in the structure of Figs. 9 and10, the groove for the brazing material is formed on the outside of theflange, as by the rib 4|. A plurality of holes 42 permit the brazingmaterial to pass to the contacting surfaces of the ilange 2| and bodyIIJ, thus providing a good joint without the opening at the end of theheader which results from using a groove on the inside of the joint,such as the groove 22 of Fig. 3.

When the headers are extruded it is of course 'possible to extrude themwith ilanges of any desired shape to serve as brackets for attaching theevaporator in its proper place in the refrigerator 6 box. A flange ofthis nature is shown at 43 in Figs. 9 and 10.

In the accumulating header of Figs. 9 and 10, the liquid trap is formedby a horizontal baille 44, which extends across the cylindrical bore ofthe header body. The body carries ribs 45, 46 and the baille is aseparate unperforated plate which is placed on ribs 45, 46 and issubsequently brazed in Place. The plate 44 is shorter than the main bodyof the header, and hence the gas which is formed can pass around theends of the plate to the gas chamber above the plate. The suction lineSla is in communication with outlet open ing 41 which is at the top ofthe header and at about the middle thereof.

During operation of the evaporator, liquid refrigerant may rise into thelower part of the accumulating header, and it is desirable to provide aslarge a liquid chamber below baille 44 as possible. However, the area ofthe gas chamber above baille 44 should be large enough that the gas`will move at relatively low velocity, so that droplets of liquidrefrigerant will not be entrained and carried into the suction line. Tosatisfy these requirements, the baille 44 is shown as locatedapproximately two-thirds of the way up from the bottom of the bore ofthe accumulator, although this exact position is not critical.

A plurality of openings 48 is formed in the bottom wall of the header,each opening 46 being in register with a conduit I6 of the mainevaporator body I6, This header may be brazed to one end of body I6 inthe manner previously explained.

If desired, the baille 44 may be extruded as an integral part of theheader, in which case, the ends of the baille must be cut away to permitgas to pass around its ends.

In the variation illustrated in Fig. 11, a distributing header '49 islocated at the bottom of the evaporator and an accumulating header I2ais attached to the upper end of each side of the U. The construction ofFig. 10 is in most respects similar to that previously described inconnection with Figs. 1 to 6 inclusive except for the shape of thedistributing headerv and its connection to the main body Ia, theselatter arrangements being shown in Fig, 12.

In this construction the header 49 is an aluminum tube which runs atright angles to the conduits I6 of the body I6, and a huid-tightconnection is made between the tube 49 and each of the conduits I 6 bymeans of a spud 5D. This spud has a reduced lower end which ts closelyin the hole 5| which communicates with passage I6, the shoulder 52serving to keep the spud from extending too far into conduit I6 duringassembly. A disc 53 of brazing compound is placed around the spud 5I]and the parts are then assembled, the spud having its reduced endprojecting into conduit I6 and its large end projecting into the tube49. Subsequent oven-brazing fuses these parts into a substantial andfluid-tight connection forming a passage between tube 49 and conduit I6.One end of the header 49 is of course closed in any preferred manner,and the liquid inlet line is connected to its other end,

By using one or more of the features described above, it is possible toconstruct an evaporator of simple and sturdy construction that will givelong and eioient service, as will be understood by those familiar withthe art of refrigeration.

I claim:

1. In an evaporator of the type in which the main body is formed by aunitary plate having 9.

'aasageai plurality of kconduits I.formed therein V:each end of eachconduit being in communication with a header, the :improvement whichcomprises: a flat surface vextending across the width of said unitaryplate, a header having Aa .flat face 4engaging said `iiat surface, said.nat surface and flat face lbeing b-razed together, the header having agroove 'adapted to hold brazing material prior to the brazing operation.

2. In an evaporator of the type in which the main bodyis formed by aunitary plate havingfa :plurality of conduits formed therein, one sideof the .plate constituting-a first flat surface and the :opposite sidehaving .projecting ribs which extend over the conduits, each end ofeachconduit 'being in communication with a header, the improvement-which comprises: a header having va first at vface engaging said firstflat surface of the 4unitary plate, ltheiunitary plate having a -sec-'ond flat surfacewhich extends across the end :of the plate and .isdisposed at right angles to :said lfirst lflat surface, the 'header'having a second hat face engaging said second fiat surface, -said flatfaces having brazed to said flat surfaces, `the header having a grooveadapted to hold brazing material prior to the 'brazing operation,

3. In an evaporator of the type in which the main body is formed by aunitary plate having -a plurality Vof conduits formed therein, one sideof the plate having a first lflat :surface and the opposite side havingprojecting ribs which extend over the conduits, each of said conduitshav- `ing one of its -ends in communication with a header, theimprovement which comprises: the lunitary plate having a second natsurface which extends across the end of the plate, the header having anolf-set flange 'formed with a rst flat face which engages the first flatsurface of the unitary plate, the header having a second at .face atright angles to the first flat face, the second flat face engaging thesecond flat surface of the unitary plate, said at faces being brazed tosaid flat surfaces.

4. The structure as setforth in claim Bin which the header has a groovelopening toward one of #said flat surfaces of the unitary plate, saidgroove 'being adapted to hold brazing material prior .to the brazingoperation.

5. The structure as set forth in-lclaim 3 in which .the header has agroove on a side away from said flat faces and has a plurality 'of holesextending from said groove to one `of said flat faces.

'6. The-structure asset forth in Vclaim 3 in which 4the header has alongitudinal passage and a series lof orices, each orifice placing oneof `the conduits of the unitary plate in communication with saidlongitudinal passage.

7. In an levaporator of the type in which the ymain body is formed by anextruded plate having ya plurality of conduits formed therein, one sideof lthe plate having 'a rs-tiiat surface and the opposite side havingprojecting ribs which extend over the conduits, each of said conduitshaving one lof its ends in communication with a distributing header, theimprovement which comprises: the extruded plate having a second flatsurface which extends across the end of the plate, the distributinghea/der being an extruded shape which has an off-set flange formed witha first flat face which engages the first flat surface o-f the extrudedIplate, the header having a second at face at right angles to the rstflat face, the second flat face engaging the second flat surface of theunitary sheet, said fiat faces being braz'ed 1to said flat surfaces.

The :structure .as set forth in claim f7 in which the vheaderis formedwith agroove opening toward fone of said nat surfaces of -the unitarysheet, said groove being adapted to lhold braz- ,5 Iing-material lpriorto the brazing operation. l

9. The structure as set forth in claim 'l in which the header :has lagroove onl-a side away from .said fiatfaces-and has a plurality of holesextendling `from said groove to one of said flat faces.

10. .The structure as set` forth in claim -7 in Which the header has `alongitudinal passage at .right angles to the conduits of the extrudedplate aandhas a series of orifices .formed in said second flat face,each orice vplacing one 'of the conduits of vthe :extruded plate incommunication with said longitudinal passage.

11. In .an evaporator Aof the type in which the main body is formed byan extruded plate having a plurality of conduits formed therein, one`side vof .the plate having a flat side Wall and lthe oppositesidelhaving projecting ^ribs which extend over the conduits, theimprovement which comprises: Ia 4'header having two lcylindricalpassages, one 'of said passages being in communication with the conduitsat one 'end of the extruded plate, and the other of said passages vbeingin communication with the conduits at the 4other end of the extrudedplate.

l2. The structure as set forth in claim l1 in which the header .-has twolaterally extending flanges, each of said anges vbeing in engagementwith the ilat side wall of the extruded plate.

13. AIn an evaporator of the type in which the main vbody is formed byan extruded plate havfing a plurality of 'conduits formed therein, one:side -of the plate having a ilat surface and the opposite side havingprojecting yribs which extend over the conduits, each `of 'said conduitsbeing in communication with a distributing header, the improvement whichcomprises: each projecting rib being yformed with an aperture, an -inlettube formed with vapertures which register with Vthe 'apertures in theribs 4and a vplurality of spuds, -each spud extending into an aperturein a rib f and an aperture in the tube, the p-arts being .brazedtogether.

14. An evaporator as 4specified in -claim 13 in which each spud has areduced portion which extends into the aperture in the `rib and an en-50 larged portion Which extends into the aperture in Ythe tube.

l5. In an evaporator of the type -in which the nmain body is formed byan extruded plate having Va plurality of conduits formed therein, one 55side of the plate having a flat surface and the opposite side havingprojecting ribs which extend over the conduits, parts of the platebetween the conduits being cutaway to form projecting tubes which .arein communication with a header, the .60 improvement which comprises: theprojecting `tubes being lof substantially Dshape in cross section, theheader being 4in the form of a tube, the

Wall of the tube being formed with a series of apertures Icorrespond-ing.in shape and location 165 with the D-shaped tubes, the tubes projectinginto vand engaging the sides of said apertures and the Wall of the tubeengaging the end of the plate between the tubes, the Ycontactingsurfaces of the tube and plate being brazed together.

116. In an evaporator of the type in which a plurality of evaporatorconduits discharge into `a header and in which ya return line leads'from the header, the 'improvement which comprises: a :partitionlocatedin .the-header between the evap- ,75 ora-tor 'conduits and :thereturn line, said Iparti-- tion dividing the header into a liquidchamber into which the evaporator conduits discharge, and a gas chamberwhich receives the gas vaporized from the liquid, the position andconstruction of said partition being such as to prevent passage ofliquid refrigerant into the gas chamber and to permit the gas to flowfrom the liquid chamber into the gas chamber at relatively low velocitythus substantially precluding the passage of liquid refrigerant into thereturn line, the return line being in communication with the gaschamber.

17. In an evaporator of the type in which a plurality of evaporatorconduits discharge into a header and in which a return line leads fromthe header, the improvement which comprises: a vertical partitionlocated in the header between the evaporator conduits and the returnline, said partition dividing the header into a liquid chamber intowhich the evaporator conduits discharge and a gas chamber which receivesthe gas vaporized from the liquid, said gas chamber being substantiallyfree from liquid, said partition closing off the entire bore of theheader eXcept for an aperture located in the partition, said aperturebeing at the upper part of the header when the evaporator is in normalposition, the return line being in communication with the gas chamber.

18. In an evaporator of the type in which a l 0 plurality of evaporatorconduits discharge into a header and in which a return line leads fromthe header, the improvement which comprises: a horizontal partitionlocated in the header between the evaporator conduits and the returnline, said partition dividing the header into a lower liquid chamberinto Awhich the evaporator conduits discharge and an upper gas chamberwhich receives the gas Vaporized from the liquid, the position andlength of said horizontal partition being such as to prevent passage ofliquid refrigerant into the gas chamber and to permit the gas to flowfrom the liquid chamber into the gas cha-mber at relatively low velocitythus substantially precluding the passage of liquid refrigerant into thereturn line, the return line being in communication with the gaschamber.

CHAS. E. HICKMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 25 Number Name Date l1,969,813 Ackerman Aug. 7,1934 2,212,912 Booth Aug. 27, 1940 2,312,087 Fitzgerald Feb. 23, 19432,145,721 Hall Jan. 31, 1939

